Simultaneous measurement of the scintillation and the Cherenkov light produced in hadronic shower development makes it possible to eliminate the effects of fluctuations in the electromagnetic shower fraction, which dominate and spoil the performance of non-compensating calorimeters. In this paper, we report on a study to separate the light signal produced by an optical calorimeter into its scintillation and Cherenkov components. To this effect, we use differences in the time structure of these two signals, as well as differences in the angular distribution of these two types of light. Both methods give useful results, especially when the numbers of scintillation and Cherenkov photons are comparable. (c) 2005 Elsevier B.V. All rights reserved.